Lots to unwrap here...
Firstly, iOS does support containerization in two ways:
1. Managed open in: Embedded within the restrictions payload is the ability to control the management of data from managed to non managed apps and accounts, and vice versa. The segmentation here is very nuanced: It's more akin to keeping personal and enterprise data separate. There's more details here: https://www.youtube.com/watch?v=fPXp6KOjj-Q
2. The second way to achieve this is by using User Enrollment, which is TRUE BYOD.
So, it is possible to support BYOD with SM and iOS
However, Apple has yet to create capabilities that allow for true network usage rules. There are some:
https://support.apple.com/en-gb/guide/deployment/depd912072f4/web
Which SM supports, but I'm guessing that what you'd want to do is specify which bearer that you'd want corporate data to go over: If that's so, Apple doesn't support this (yet)